The present invention relates to a data storage device and a control method therefor, and more particularly to a data storage device in which a head is provided with a heater for adjusting the clearance between the head and a medium, and to a control method for the heater.
Data storage devices using various types of media such as optical disks, magnetic tapes and semiconductor memories are known in the art. Among them, hard disk drives (hereinafter refer to as HDDs) have become popular as storage devices for computers to such an extent that they are one type of the storage devices indispensable for today's computers. Further, not limited to computer systems, HDDs are expanding more and more in application because of their excellent characteristics. For example, HDDs are used for moving picture recording/reproducing devices, car navigation systems, cellular phones, and removable memories for use in digital cameras.
A magnetic disk used in the HDD has a plurality of data tracks that are concentrically formed. A plurality of pieces of servo data each having address information, and a plurality of data sectors each including user data, are written to each data track. A plurality of data sectors are written between servo data areas. By accessing, according to the address information of the servo data, a desired data sector by use of a head element of a head slider supported by an actuator that pivotally moves, it is possible to write data to the data sector or to read data from the data sector.
In order to improve the recording density of a magnetic disk, it is important to reduce the clearance between the magnetic disk and a head element flying above the magnetic disk. For this reason, some mechanisms for adjusting the clearance are proposed. In one example of the mechanisms, a head slider includes a heater, and the clearance is adjusted by heating a head element by use of the heater (for example, refer to patent document 1 (Japanese Patent Laid-open No. 5-20635)). In this specification, this is called TFC (Thermal Flyheight Control). According to the TFC, an electric current is supplied to a heater to generate heat, which causes a head element to protrude. This makes it possible to reduce the clearance between a magnetic disk and a head element.